Pressure sensing devices and methods, control devices and methods of

Abstract

A device for sensing pressure at a source thereof comprising a housing with a fluid pressure responsive diaphragm movable therein for defining therewith an expansible chamber for communication with the source of pressure the magnitude of which is to be sensed, and a transducer. The transducer includes a body of magnetoelastic material of generally annular form positioned within the housing and having magnetic properties which vary as a function of the stress to which the body is subjected in response to movement of the diaphragm. Electrical circuitry responds to stress-induced changes in the magnetic properties to produce an electrical signal having a value which is a function of the magnitude of the fluid pressure. The device includes an actuator, which is movable with the diaphragm, for accepting and retaining a sector of the annular body and a cradle generally fixed in relation to the housing for accepting and retaining a diametrically opposite sector of the annular body. An increase in the fluid pressure in the expansible chamber tends to compress the annular body between the actuator and the cradle. A smart pressure switch including logic circuitry and the pressure sensing device, air conditioning systems incorporating such sensing and control devices, and methods of sensing pressure and controlling the operation of air conditioning systems are also described.